Apparatus for freezedrying material with loading and discharging means

ABSTRACT

Freeze drying apparatus is shown which comprises a freeze drying chamber with a charging lock at one end through which materials to be freeze dried are introduced to the chamber. At the other end of the chamber a discharge lock is provided. Elevator means are provided in the lock and conveying means are provided for conducting materials through the freeze drying chamber from a charging lock to the discharge lock.

United States Patent 1 Lorentzen et al, Nov. 6, 1973 APPARATUS FOR FREEZEDRYING 3,382,586 5/1968 Lorcntzen 34/92 MATERIAL WITH LOADING AND 3,243,892 4/1966 Ullrich et al 4 34/242 V 3,354,609 ll/l967 Nerge et al, 34/92 X DISCHARGING MEANS 3,234,661 2/1966 Nerge 34/5 X [76] Inventors: Jorgen Lorentzen, Alf.

Christensensvej l0, Naerum; Verner Christiansen, Kongebakken 48, Primary Examiner-William F. ODea RQSkIIdC; Carl Carlsen, Tvaefvej Assistant Examiner-William C. Anderson Vi all of Denmark Attorney-Albert C. Nolte, Jr. et al.

[22] Filed: Aug. 24, 1971 [2l] Appl. No.: 174,448

[57] ABSTRACT [30] Foreign Application Priority Data Aug. 25, 1970 Denmark 4341 Fr z ying pp r s is sh wn which comprises a freeze drying chamber with a charging lock at one end [52] U.S. Cl. 34/92, 34/242 ugh whi h material to be freeze dried are intro- [51] Int. Cl. F26b 5/06 due d t0 h chamber. A he other end of the chamber [58] Field of Search 34/5, 92, 242; a discharge lock is provided. Elevator means are pro- 214/17, 17 A vided in the lock and conveying means are provided for conducting materials through the freeze drying cham- [56] References Cited ber from a charging lock to the discharge lock.

. UNITED STATES PATENTS 3,192,645 7/1965 Oetjen 34/5 X 14 Claims, 7 Drawing Figures PATENTEDnnv 61975 3,769,717

PATENTEDNUV 6 ma I 3.769.717

sum u UF. 4

FIG. 7

- FIG. '6

APPARATUS FOR FREEZEDRYING MATERIAL WITH LOADING AND DISCHARGING MEANS The invention relates to an apparatus for freezedrying material, comprising a vacuum chamber with lock means for charging and discharging material.

According to the invention the vacuum chamber may be connected with at least two sets of water vapour condensing surfaces located within or outside the vacuum cabinet, and that separately can be isolated from the vacuum chamber. The isolation means are arranged in such a way that at any time at least one set of condensing surfaces is not isolated from the vacuum chamber. In this case a certain capacity is available for condensing for maintaining vacuum in the vacuum chamber, and simultaneously one set of condensing surfaces can be deiced so that the latter set is prepared for subsequent condensing.

The apparatus according to the invention may have means for radiation heat transfer to freezedrying goods forming a flat layer of granules, preferably substantially free from small particles. It has turned out that hereby a specially effective freezedrying can be obtained.

The lock means according to the invention may comprise at least one lock chamber that. is arranged to be sealingly closed to the atmosphere and to the vacuum chamber into different temperature zones. Preferably the apparatus comprises means for altering the division into temperature zones, by which an adaption to different kinds of freeze-drying goods may be obtained.

The apparatus may be arranged in such a manner that it comprises lock means for charging of one tray of freezedrying goods at a time into the vacuum chamber to a lifting mechanism, which is arranged for lifting the trays one step at a time to make a pile or stack of trays, that rest each on its own level of the lifting mechanism on a level with a horizontal conveyor track for trays, which conveyor tracks are situated between the heat plates. Herebya simple and practical construction for conveying the trays through the apparatus is obtained. In contrast to such known apparatuses where the trays are led in a zigzag course through the vacuum chamber, there is hereby obtained the possibility of dichamber, and a vacuum pump for the lockchamber may be independent of the vacuum chamber, respectively of means for maintaining the vacuum in the vacuum chamber, and a closing member between the lock chamber and the vacuum chamber may preferably have its sealing abutment on the lock chamber side, so

that over-pressure in the lock chamber in relation to the vacuum chamber presses the closing member to sealing abutment, and a closing member between the atmosphere and the lock chamber may preferably have its sealing abutment on the atmosphere side, so that the atmospheric pressure by sub-pressure in the lock chamber presses the closing member to sealing abutment. By use of a special vacuum pump for the lock chamber it is obtained that the passing of material through a lock will not be detrimental to the vacuum in the vacuum chamber, and herebyit is obtained that a vacuum pump with relatively small capacity may be used for the vacuum chamber, as it only has to provide for removal'of the relatively small amount of air, that appears in the vacuum chamber from the drying goods and from any leakages. By the mentioned positioning of the closing members an effective sealing is obtained in a simple manner.

Between a lock chamber and the vacuum chamber or a vacuum suction conduit connected thereto there may be arranged a vacuum conduit with a controllable valve for pressure equalization before opening between the lock chamber so that the closing member is easily opened and the vacuum chamber.

The apparatus may be arranged in such a way that it has a number of heat plates located over each other, which are arranged in a number of sets in plate carriages, for instance four or more, each of which having connecting means for heat energy supply to the plates in the plate carriage, preferably for circulation of a heat medium, the apparatus having means for maintaining different heat levels in two or more plate carraiges for providing different temperature zones in the vacuum chamber. By the dividing up in plate carriages inspection and repair are facilitated as is the division of the viding the vacuum chamber into temperature zones.

The apparatus may comprise means for pushing forwards trays on the conveyor tracks one tray-length at a time from an entry elevator to an exit-- elevator. Hereby a simple andinexpensive construction is obtained.

The apparatus may be arranged in such a manner that the trays during the conveying from the entry elepair the vacuum in the vacuum chamber, corresponding to an absolute pressure of below the vapour pressure of water at 0 C, for instance an absolute pressure of only 1 Torr.

The apparatus may be arranged in such a way that it comprises an exit elevator for receiving trays from the horizontal conveyor tracks as the result of the pushing forward of trays on these conveyor tracks through the of a set or a stack oftrays, to move a little bit farther in the conveying direction towards in the vacuum chamber fixedly located, on a vertical line situated stopping means to secure that the trays are brought into line with each other before the lowering inthe elevator. Hereby the passing out of the trays is faciliated. 'In the drawings an apparatus according to the invention is schematically shown.- 7

FIG. 1 shows the apparatus in horizontal sectional view, seen from above,

FIG. 2 the same in vertical longitudinal sectional view,

FIG. 3 the same in vertical sectional view, at one end of the apparatus,

FIG. 4a vertical partial sectional view of a plate carriage with heat plates and tracks for trays,

FIG. 5 section of a lock or sluice mechanism for charging trays into the apparatus,

FIG. 6 a diagram showing the supply of heat to the plate carriages, and

FIG. 7 adiagram showing the vacuum connections to a vacuum chamber and a charginglock.

The apparatus comprises an oblong cabinet 1, that constitutes a vacuum drying chamber, in which a sufficiently high vacuum for freezedrying is maintained.- The cabinet 1 has substantially cylindrical section and convex end walls, at least one of which can be opened or is detachable, not shown.

In the cabinet a number of plate carriages are placed, for instance five, that each has a frame with vertical rods 2, upon which horizontal heat plates 3 are fastened, being arranged for the circulation of a heat medium, whereby the surfaces of the heat plates can emit heat rays upwards and downwards. Furthermore, horimedium zontal tracks or rails 4 are fastened, suitably heat isolated from the heat plates, on the rods 2. The plate carriages are placed end to end so that the tracks 4 lie level with each other. For instance, there may be seven sets of tracks above each other so that the tracks 4 at the two sides of the plate carriages form horizontal conveyor tracks for trays 5, which preferably consist of aluminium andat each side comprise slide fittings 6, pref? erably consisting of polytetrafluorethylene (PTFE), so that the trays can slide easily on the tracks 4.

At oneend the cabinet 1 has an aperture for lock or sluice means including a lock chamber 7, a hydraulic cylinder 8 for pushing one tray at a time into the lock chamber 7 through a closable aperture 9, means 10 for charging one tray at a time from the lock chamber 7 through a closable aperture-11 to the vacuum chamber in the cabinet 1. In the lock chamber the tray 5 will rest on a supporting means 12, having teeth, which cooperates with a gear-wheel in the means 10 driven by a mo tor, not shown, so that the supporting means 12'is introduced into the cabinet with thetray resting upon it. Thereafter, the gear-wheel again draws the supporting means out into the lock chamber, while the tray is maintained in the cabinet. In thecabinet the tray will rest upon a lifting mechanism 13, that is arranged to lift the tray a relatively small distance upwards, whereafter its edges are gripped by projections 14 on endless, vertically extending bands l5. The projections 14 are located with a'pitch corresponding to the vertical dis- I tance between the tracks 4 in the plate carriages. The

two bands are arranged to be moved upwards, one projection-pitch at a time. The lifting mechanism 13 and the bands 15 together form an entry elevator. It is implied that'the elevator is empty at the beginning. By charging the trays one at a time, there will, on the projections 14 facing each other be formed a pile of seven trays 5, lying level with the tracks4 in the plate carriages.

Between the mentioned elevator, being an entry elevator, and the end of the cabinet 1 there is arranged a pushing mechanism comprising a hydraulic-cylinder 16 and means 17, arranged to push at the edge of the trays 5 resting on the projections 14, by means of which the trays are pushed in upon the tracks 4. When trays previously have been placed on these tracks, these trays are pushed forwards on the tracks. The length of movementby means of the pushing mechanism -16, '17 is equal to the length of a tray.

At the other end of the cabinet there is a similar elevator, being an exit elevator, and being provided for receiving trays from the tracks 4. Hereby there is produced a pile of trays on the exit elevator, resting on its projections 14. This exit elevator is arranged to be lowered one projection-pitch at a time and thereby to deliver one tray at a time to the lifting apparatus 13 in question, here being arranged to lower one tray at a time down onto a means 12, which moves the tray out through the closable aperture 11 in question at the other end of the cabinet, where a discharge lock 18 is located, corresponding to the charge 7-11, apart from the fact that the former instead of the hydraulic cylinder 8 has a hydraulic cylinder 19 for pushing out a tray from the lock chamber. The two endless bands of the discharge elevator and a frame for these are arranged movably in longitudinal direction of the cabinet and are connected with a hydraulic cylinder 20 for moving the bands a little bit forwards and backwards. When the trays are being transferred from the tracks 4 to the projections 14 on the discharge elevator, the bands thereof will be in the position shown at the left in FIG. 1. Thereafter, they are moved a little to the right, whereby the trays 5 on the projections 14 hit fixedly located stopping means 21, by which the trays are brought into a position exactly vertical above each other, so that they are brought to the discharge lock in exactly the same position. l

The cabinet 1 at its bottom has a widening 22, in which two sets of water vapour condensing tubes 23 and 24 are located one in each compartment 25 and 26, which are separated from the vacuum chamber in the cabinet by means of horizontal walls 27 and 28, and which are separated from each other by a vertical wall 29(Between the edges of the walls 27 and 28 and the top edge of the wall 29 an aperture is provided from the vacuum chamber to each of the compartments 25 and 26. A swingable .flap 30 in its two extreme positions closes the aperture of the one compartment 25 and of the other compartment 256 respectively. By means of a closeable valve 30 and 31 -respectively,'the two compartments 25 and 26 are 'connected with a chamber 32, in which a heat tube 33 is located, and in which, during operation, water is kept at a temperature by which the vapour pressure of the water is a small fraction of one atmosphere, for instance 1020 C. The chamber 32 comprises an overflow 34, through which surplus water may flow without impairing the vacuum in the chamber 32. The water removing system is not shown.

In FIG. 5 there is very schematically shown lock means that may be used either as charging lock means or as discharging lock means. An aperture 35 between the lock chamber and the vacuum chamberin the cabinet 1 is closeable by means of a valve flap 36, that by means of a hydraulic cylinder 37 can be swung from the shown open position to a closed position, where the flap is in contact with the sealing means 38 around the aperture 35. In the figure the toothing on the under side of the supporting means 12 and a gear-wheel 39 for backand forwards moving the supporting means 12 are shown. In this FIG. 5 charging of the trays 5- takes place in the longitudinal direction of the lock chamber for the sake of the clearness. At theend opposite the aperture 35 the-lock chamber comprises an aperture, which is shown closed by means of a valve flap 40, that is moved'by a hydraulic cylinder 41 from the illustrated closed positionto a not shown open position. In the shown closed position the valve flap 40 bears against the sealing means 42. Thus, at both ends of the lock chamber the valve flaps are located in such a manner that the pressure difference that appears during operation acts to seal the flap.

In FIG. 6 the circulation of heat medium through the heat plates 3 is shown. The apparatus comprises a reservoir for heat medium which is connected to a conduit 43, from which a conduit 44 branches off to a valve mechanism 45, from where a conduit 46 branches off to a circulation pump 47 to a heat plate carriage 48, in which heat medium for instance may be led through a lower set of heat plates and therefrom through an upper set of heat plates to a discharge conduit 49, that leads back to the reservoir for heat medium. In the corinection between the pump 47 and the heat plate carriage a heat-sensing means 50 is located, operating the valve 45 in such a manner that a desired temperature of the heat plates in the heat plate carriage 48 is achieved. From the conduit 43 another conduit 51 branches off, in a similar way leading to a valve mechanism 52, from which a conduit 53 branches off to a circulation pump 54 to a heat plate carriage, in which heat medium, for instance, may be led through a lower set of heat plates 3 and therefrom through an upper set of heat plates to a discharge conduit 54, which is connected to the conduit 49 and which leads back to the reservoir for heat medium. In the connection between the pump 54 and the heat plate carriage 55 a sensing means 56 is located, operating the valve 52 in such a way that hereby a desired temperature of the heat platesin the heat plate carriage 55 is achieved. The other heat plate carriages may be operated in similar way. There is'the possibility of having two or more heat plate carriages operated at the same temperature.

In FIG. 7 something essential is shown regarding the control of vacuum in the cabinet 1 and the lock chamber or both lock chambers. To the cabinet 1 is con nected a suction conduit 57 to a vacuum pump 58 To' the lock chamber 7 is connected a suction conduit 59 to another vacuum pump 60. A closeable valve 61 is located in the conduit 59. Between the lock chamber 7 and the conduit 57a conduit 62 with a closable valve 63 is arranged. By means of the valves 61 and 63 an equilization of the pressure between the cabinet 1 and the lock chamber 7 may be obtained,.before the closing means 36 is opened. I

As an example of the logical'control of the motion operations the steps for the charge lock will be studied tor 64, initiator 65, and initiator 68 are activated. In

step 2 the'tray 5 is pushed in position in the lock chamber 7 until the initiator 66 is activated. Thereby step 3 is initiated, in which the tray-pusher moves back out of the lock chamber, confer the hydraulic cylinder 8 in FIG. 1, however, FIG. 5 differing from FIG. 1 by the fact that the cylinder 8 in FIG. 5 is thought located opposite-the end of the lock chamber. The mentioned tray-pusher moves outwards, until an end switch'registers that it is back in the initial position, by which step 4 is'initiated.

In step 4 the lock flap 40 is closed, and the valve 59 is opened. During this the valve 63 and a valve 69 have been closed. Hereafter, evacuation of the lock chamber 7 takes place by means ofthe vacuum pump 60. A certain evacuation-time having passed, and provided that a pressure-initiator 70 is activated by the correct vacuum in the lock chamber being obtained, step 5 begins.

.During this the pressure equalization valve 63 between the lock chamber 7 and the cabinet 1 is opened, and the valve 59 is closed. After the response of an adjustable timing relay, arranged in a not shown control board and determining the time gap between the charge of the single trays into the cabinet 1, step 6 beings. During this the lock flap 36 is opened, whereby the initiator 67 is activated, and the valve63 is closed. Simultaneously the timing relay'mentioned in step 5 starts again. When the initiator 67 has been activated, step 7 follows. During this the supporting means 12 is moved by means of the gear-wheel 39 inwards into the cabinet 1 through the aperture released by the flap 36 and carries the tray 5 into position in the cabinet 1. Hereby an initiator 71 is activated, starting step 8 during which the tray by the lifting mechanism 13 is lifted up onto the band conveyor-15. Thereafter step 9 follows, during which the supporting means 12 is carried back into thelock chamber until the initiator 65 is activated and starts step'10. During this the lock flap 36 is closed and an initiator 72 is activated and starts step 11. During'step 11 the valve 69 is opened, and air flows into the lock chamber 7, whereby the pressure herein is brought up to atmospheric pressure. Sometime having passed the next step follows, during which the valve 69 is closed and the lock flap 40 is opened, by which the initiator 64 is activated. Simultaneously a new tray is lifted into position in front of the lock' flap 40, whereby the initiator 68 is activated. Hereby the logical conditions of step 1 is'fulfilled and step 1 is repeated, and a new cycle is initiated.

Corresponding steps are used in connection with the dischargelock l8, and the initiators controlling motions and pressure in this lock are correspondingly coupled to the separate steps so'that the necessary logic conditions of each step of this lock are fulfilled before the next step is effected:

Furthermore, initiators are used in-acorresponding way for operating the chargeand discharge band elevators 15, the cooperation of these with the lifting mechanism 13, the pushing mechanism 16, 17, the hydraulic cylinder 20.

We claim: g

1. F reezedrying' apparatus of the type comprising an oblong vacuum chamber, means for providing and maintaining freezedrying vacuum in the chamber, a material charging lock at one end of the chamber, a material discharging lock at the other end of the chamber, means for carrying material in the chamber from the charging lock to the discharging lock, and means for supplying heat to the material in the chamber, characterised in, that the charging lock is arranged for introducing one material tray at a time, that in the chamber near the charging lock means are provided for receiving one tray at a time and stepwise. vertical movement for forming a stack of trays, and means for horizontal movement of the trays of such stack from the area near the charging lock to the area nearthe discharging lock, that in the chamber near the discharging lock means are provided for receiving a stack of trays and moving them stepwise vertically for delivering one tray at a time to the discharging lock, the latter being arranged for passing out one tray at a time.

2. Freezedrying apparatus according to claim 1, wherein a number of horizontal heat plates are arranged above each other in the freezedrying chamber, characterised in that the heat plates are arranged in a number of units arranged one after another in the longitudinal direction of the chamber.

3. Freezedrying apparatus according to claim 1, characterized in that the vertical movement means near the discharging lock are arranged to be, after receipt of a stack of trays, moved a little way in the transport direction of the trays through the freezedrying chamber and that stop means are arranged in the chamber for stopping the trays to provide a precise vertical stack of trays.

4. Freezedrying apparatus according to claim 1, characterized in that the charging lock has a tray supporting member arranged to be moved into the freezedrying chamber for carrying a tray into the freezedrying chamber and for delivering to vertical movement means and that rails are arranged in the freezedrying chamber for supporting the trays being pushed forward on said rails.

5. Freezedrying apparatus according to claim 1 characterized in that a discharging lock has a tray supporting member arranged to be moved out of the freezedrying chamber for carrying a tray from the freezedrying chamber and for receiving a tray from the vertical movement means, and that rails are arranged in the freezedrying chamber for supporting the trays being pushed forward on said rails.

6. Apparatus as claimed in claim 1 wherein each lock 1 chamber comprises a closing member between a chamber of the lock and the vacuum chamber, said closing member having sealing abutment on the lock chamber side thereof so that over-pressure within the lock chamber in relation to the vacuum chamber presses the closing member to sealing abutment and a closing member between atmosphere and the .lock chamber, said latter closing member having sealing abutment on that side thereof exposed to atmosphere so that atmospheric pressure presses the closing member into sealing abutment.

7. Apparatus as claimed in claim 1 wherein between a lock chamber and the vacuum chamber a vacuum conduit is provided, said conduithaving a controllable valve for equalization of said chambers before the opening of a lock chamber closure member between the lock chamber and the vacuum chamber.

8. Apparatus as claimed in claim 2 wherein means are provided for maintaining different heat levels in different heating plates whereby different temperature zones in the vacuum chamber are obtained.

9. Apparatus as claimed in claim 1 wherein said means for horizontal movement of said trays comprises a conveyor having means for pushing forward trays thereon one track length at a time between said vertical movement means.

10. Apparatus as claimed in claim 9 wherein said conveyor comprises horizontal rails independent of said heat plates, said rails being of stainless steel and said trays being of aluminum and having slide shoes of polytetrafluorethylene.

11. Apparatus as claimed in claim 1 comprising an entry elevator and an exit elevator and means for synchronizing operation of said charging and discharging locks with said entry elevator and said exit elevator, said synchronizing means comprising a logic-control means of the various operation-steps with initiators for controlling the separate steps in such a manner that at any time a preceding step is fulfilled before the next step is initiated.

l2. Freezedrying apparatus according to claim 1, characterised in that a lock chamber in the charging lock or the discharging lock or both is connected with a vacuum pump which is independent of a vacuum pump for the freeze drying chamber, and that the lock chamber is connected with the freezedrying chamber by means of a conduit in which there is arranged a valve which is kept closed during formation of vacuum in the lock chamber and is opened previously to opening the connecting aperture between the lock chamber and the freezedrying chamber.

13. Freezedrying apparatus according to claim 12 wherein a number of horizontal heat plates are arranged above each other in the freezedrying chamber, characterized in that the heat plates are arranged in a number of units arranged one after another in the longitudinal direction of the chamber.

14. Freezedrying apparatus according to claim 12 characterized in that the vertical movement means near the discharging lock are arranged to be moved, afterreceipt of a stack of trays, a little way in the transport direction of the trays through the freezedrying chamber and that stop means are arranged in the chamber for stopping the trays to provide a precise vertical stack of trays. 

1. Freezedrying apparatus of the type comprising an oblong vacuum chamber, means for providing and maintaining freezedrying vacuum in the chamber, a material charging lock at one end of the chamber, a material discharging lock at the other end of the chamber, means for carrying material in the chamber from the charging lock to the discharging lock, and means for supplying heat to the material in the chamber, characterised in, that the charging lock is arranged for introducing one material tray at a time, that in the chamber near the charging lock means are provided for receiving one tray at a time and stepwise vertical movement for forming a stack of trays, and means for horizontal movement of the trays of such stack from the area near the charging lock to the area near the discharging lock, that in the chamber near the discharging lock means are provided for receiving a stack of trays and moving them stepwise vertically for delivering one tray at a time to the discharging lock, the latter being arranged for passing out one tray at a time.
 2. Freezedrying apparatus according to claim 1, wherein a number of horizontal heat plates are arranged above each other in the freezedrying chamber, characterised in that the heat plates are arranged in a number of units arranged one after another in the longitudinal direction of the chamber.
 3. Freezedrying apparatus according to claim 1, characterized in that the vertical movement means near the discharging lock are arranged to be, after receipt of a stack of trays, moved a little way in the transport direction of the trays through the freezedrying chamber and that stop means are arranged in the chamber for stopping the trays to provide a precise vertical stack of trays.
 4. Freezedrying apparatus according to claim 1, characterized in that the charging lock has a tray supporting member arranged to be moved into the freezedrying chamber for carrying a tray into the freezedrying chamber and for delivering to vertical movement means and that rails are arranged in the freezedrying chamber for supporting the trays being pushed forward on said rails.
 5. Freezedrying apparatus according to claim 1 characterized in that a discharging lock has a tray supporting member arranged to be moved out of the freezedrying chamber for carrying a tray from the freezedrying chamber and for receiving a tray from the vertical movement means, and that rails are arranged in the freezedrying chamber for supporting the trays being pushed forward on said rails.
 6. Apparatus as claimed in claim 1 wherein each lock chamber comprises a closing member between a chamber of the lock and the vacuum chamber, said closing member having sealing abutment on the lock chamber side thereof so that over-pressure within the lock chamber in relation to the vacuum chamber presses the closing member to sealing abutment and a closing member betWeen atmosphere and the lock chamber, said latter closing member having sealing abutment on that side thereof exposed to atmosphere so that atmospheric pressure presses the closing member into sealing abutment.
 7. Apparatus as claimed in claim 1 wherein between a lock chamber and the vacuum chamber a vacuum conduit is provided, said conduit having a controllable valve for equalization of said chambers before the opening of a lock chamber closure member between the lock chamber and the vacuum chamber.
 8. Apparatus as claimed in claim 2 wherein means are provided for maintaining different heat levels in different heating plates whereby different temperature zones in the vacuum chamber are obtained.
 9. Apparatus as claimed in claim 1 wherein said means for horizontal movement of said trays comprises a conveyor having means for pushing forward trays thereon one track length at a time between said vertical movement means.
 10. Apparatus as claimed in claim 9 wherein said conveyor comprises horizontal rails independent of said heat plates, said rails being of stainless steel and said trays being of aluminum and having slide shoes of polytetrafluorethylene.
 11. Apparatus as claimed in claim 1 comprising an entry elevator and an exit elevator and means for synchronizing operation of said charging and discharging locks with said entry elevator and said exit elevator, said synchronizing means comprising a logic-control means of the various operation-steps with initiators for controlling the separate steps in such a manner that at any time a preceding step is fulfilled before the next step is initiated.
 12. Freezedrying apparatus according to claim 1, characterised in that a lock chamber in the charging lock or the discharging lock or both is connected with a vacuum pump which is independent of a vacuum pump for the freeze drying chamber, and that the lock chamber is connected with the freezedrying chamber by means of a conduit in which there is arranged a valve which is kept closed during formation of vacuum in the lock chamber and is opened previously to opening the connecting aperture between the lock chamber and the freezedrying chamber.
 13. Freezedrying apparatus according to claim 12 wherein a number of horizontal heat plates are arranged above each other in the freezedrying chamber, characterized in that the heat plates are arranged in a number of units arranged one after another in the longitudinal direction of the chamber.
 14. Freezedrying apparatus according to claim 12 characterized in that the vertical movement means near the discharging lock are arranged to be moved, after receipt of a stack of trays, a little way in the transport direction of the trays through the freezedrying chamber and that stop means are arranged in the chamber for stopping the trays to provide a precise vertical stack of trays. 